Error interface in Go - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare the error interface method.

Go

type error interface {
	[1]() string
}

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Aerror

BError()

CErrorString

DError

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase 'error' instead of 'Error' as method name.

Adding parentheses in the method name in the interface declaration.

The error interface requires a method named Error that returns a string.

2fill in blank

medium

Complete the code to implement the error interface for MyError type.

Go

type MyError struct {
	msg string
}

func (e MyError) [1]() string {
	return e.msg
}

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AErrorString

Berror

CError

DString

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'error' or 'String' instead of 'Error' as method name.

Forgetting to return a string.

The method to implement the error interface must be named Error and return a string.

3fill in blank

hard

Fix the error in the function signature to correctly implement the error interface.

Go

func (e *MyError) [1]() string {
	return e.msg
}

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AError()

BError

Cerror

DErrorString

Attempts:

3 left

💡 Hint

Common Mistakes

Including parentheses in the method name in the declaration.

Using lowercase method name.

The method name must be exactly Error without parentheses in the declaration.

4fill in blank

hard

Fill both blanks to create a function that returns an error interface value.

Go

func NewError(msg string) [1] {
	return &[2]{msg}
}

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Aerror

BMyError

Cmsg

Attempts:

3 left

💡 Hint

Common Mistakes

Returning concrete type instead of interface.

Not using pointer to struct.

The function returns the error interface type and returns a pointer to MyError struct initialized with the message.

5fill in blank

hard

Fill all three blanks to check if an error is nil and print its message.

Go

var err [1] = NewError("fail")
if err [2] nil {
	fmt.Println(err.[3]())
}

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Aerror

B!=

CError

D*MyError

Attempts:

3 left

💡 Hint

Common Mistakes

Using pointer type instead of interface for error variable.

Using == instead of != to check error.

Calling method with wrong name or missing parentheses.

Declare err as type error, check if it is not nil, then call its Error() method to print the message.